I have worked in high tech in the northeast for years (somewhere near Boston). Jeans, t-shirts, clean clothes, no holes in the clothes, no severely worn clothes. Technical conferences are typically the same, although I avoid jeans for long trips only because they are too heavy to carry a lot of them in a suitcase. One time years ago I was going to drop by a wedding on the way back from a technical conference so I had a suit with me. At the last minute I was asked to give a talk to the full conference so I asked the chair “should I wear the suit”. His reply was “no, people will think that you are not technical”.
I suspect that some companies might be different, even radically different. I wouldn’t dress like this for an interview at a bank or investment company, but then I wouldn’t interview at a bank or investment company.